A worthy point Tenacious Green, when I get a PC Advisor mag I always look to see if there are some programs I may actually use, if not now then perhaps in the forseeable future. I also make it a point to check to see if it requires online registration and if it does I do it then even if I won't be using the program for a while. The reason I do this is that you may find if you want to try a particular program 6 months later that the registration site has been closed, if you've already registered and have a serial number you're ok and can reinstall and run the program.
As an example of this I have CDX Rescue which I registered at the time and have used twice to successfully get information off a damaged disk. If you still have the PCA disk and wish to use it but haven't the serial number I'm afraid you've had it as the site is gone, as has the company sadly.